Historically, toxic baits for controlling crawling insects, such as cockroaches, have been water-based. With cockroaches especially, water is presumed necessary for good bait performance. Unfortunately, water-based bait products rapidly lose effectiveness due to water loss, spoilage, rancidity or breakdown of active ingredients and other factors. Studies of water-based paste baits have confirmed that water loss, repellant properties of active ingredients, and insecticide resistance are the most important factors affecting bait performance, Appel, A. G. J. Econ Entomol 85 (4):1176-1183 (1992), Robinson, W. H. Proceedings of the National Conference on Urban Entomology 77-91 (1992), and Rust, N. K. "Managing Household Pests", in Advances in Urban Pest Management, G. W. Bennett and M. Owens (eds), Van Norstrand Reinhold, New York 335-368 (1986).
The above problems have been solved by developing superior baits that are fat-based suspensions, designed to be applied, for example, as pastes to cracks and crevices for control of cockroaches, ants and other insects. These fat-based baits have the advantage of superior durability with prolonged attractiveness and stability of active and inert ingredients. Fat-based baits have the additional advantage of water repellency, allowing for durability in excessively damp environments. In some environments stability and browning remain a problem in certain formulations.